Copper sulphate solution reacts with sodium hydroxide solution to form a precipitate of copper hydroxide according to the equation: 2 NaOH + CuSO 4 → Na 2 SO 4 + Cu ( OH ) 2 ↓ i) What mass of copper hydroxide is precipitated by using 200 gm of sodium hydroxide? [ H = 1 , O = 16 , Na = 23 , S = 32 , Cu = 64 ] (ii) What is the colour of the precipitate formed?

(i) 2 NaOH + CuSO 4 → Na 2 SO 4 + Cu ( OH ) 2 ↓ Molecular mass of sodium hydroxide = 2 ( 23 + 16 + 1 ) = 80 g Molecular mass of copper hydroxide = 64 + 32 + 2 = 98 g 98 g of Cu ( OH ) 2 is precipitated by using 80 g of NaOH . x g of Cu ( OH ) 2 is precipitated by using 200 g of NaOH . x = 98 80 × 200 g = 245 g of Cu ( OH ) 2 (ii) A light blue precipitate of copper hydroxide will be formed.

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The vapour density of a mixture containing $N O_{2} a n d N_{2} O_{4} i s 38.3 a t 27^{o} C$ . Calculate the mole of $N O_{2} i n 100 g$ mixture.

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Important Questions on Some Basic Concepts of Chemistry

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

Calculate the weight of

10^{22}

atoms of carbon. [

C = 12

, Avogadro’s No.=

6 \times 10^{23}

]

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

The common isotopes of carbon are

{}^{12}C

and

{}^{13}C

. The average mass of carbon is

12.01115 amu

. What is the abundance of the

{}^{13}C

isotope?

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

Two elements

A

and

B

which form

0.15

moles of

A_{2} B

and

{AB}_{3}

type compounds. If one mole of each

A_{2} B

and

{AB}_{3}

weigh equally, then the atomic weight of

A

is____times of atomic weight of

B

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

A and B react to produce C according to the following chemical equation
$2 A + B \to 2 C$

A, B and C are the formulas for three gaseous substances. The vapour densities of A and B are 32 and 16 respectively. Find out the vapour density of C.

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

One mole of dioxygen gas at

STP

is equal to

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

Copper sulphate solution reacts with sodium hydroxide solution to form a precipitate of copper hydroxide according to the equation:

$2 NaOH + {CuSO}_{4} \to {Na}_{2} {SO}_{4} + Cu {(OH)}_{2} ↓$

i) What mass of copper hydroxide is precipitated by using $200 gm$ of sodium hydroxide?

$[H = 1, O = 16, Na = 23, S = 32, Cu = 64]$

(ii) What is the colour of the precipitate formed?

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

Which symbol replaced the unit of atomic mass, amu?

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

The molecular mass of methane $({CH}_{4})$ is $16 u$ .

What is the mass of 1 GMM of CH4

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

The unit of atomic mass,

amu

is replaced by

u

, here

u

stands for

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

What will be the mass of one atom of

{}^{12}C

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

3 g

of acetic acid is added to

250 m L

0.1 M H C l

and the solution made up to

500 m L

. To

20 m L

of this solution

\frac{1}{2} m L

5 M N a O H

is added. The

p H

of the solution is ________
[Given:

p K a

of acetic acid

= 4.75,

molar mass of acetic acid

60 g / m o l, \log 3 = 0.4771

, Neglect any changes in volume]

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

Natural abundances of

^{12} C

and

^{13} C

isotopes of carbon are

99 %

and

1 %

respectively. Assuming they only contributes to the molecular weight of

C_{2} F_{4}

, the percentage of

C_{2} F_{4}

having a molecular mass of

101

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

Consider an imaginary ion

{}_{22}^{48}X^{3 -}

. The nucleus contains '

a

%

more neutrons than the number of electrons in the ion. The value of '

a

' is

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

Calculate mass of

3.01 \times 10^{24}

atoms of an element having atomic mass

21.13

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

The average molar mass of chlorine is

35.5 g {mol}^{- 1}

. The ratio of

{}^{35}{Cl}

{}^{37}{Cl}

in naturally occurring chlorine is close to :

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

Chlorine has two naturally occurring isotopes.

^{35} C l

and

^{37} C l

. If the atomic mass if

C l

is 35.45, the ratio of natural abundance of

^{35} C l

and

^{37} C l

is closest to

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

3.011 \times 10^{22}

atoms of an element weigh

1.15 gm

. The atomic mass of the element is.

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

If we consider that

\frac{1}{6},

in place of

\frac{1}{12}

, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

If molecular mass and atomic mass of sulphur are

256

and

32

respectively, its atomicity is

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Mass

Number of protons, neutrons and electrons in the element

_{89}^{231} Y

The vapour density of a mixture containing NO2 and N2O4 is 38.3 at 27oC . Calculate the mole of NO2 in 100 g mixture.

Important Questions on Some Basic Concepts of Chemistry

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The vapour density of a mixture containing $N O_{2} a n d N_{2} O_{4} i s 38.3 a t 27^{o} C$ . Calculate the mole of $N O_{2} i n 100 g$ mixture.